Refuting The Best Argument Against God

In 2013, Australian philosopher Graham Oppy published a book called The Best Argument Against God, in which he presents a case for naturalism (the view that nature is all that exists) over and against theism (the view that God exists). In a nut shell, his argument is that naturalism is simpler than theism, and that there are no reasons, evidence or arguments that favour theism. In Oppy’s words:

“We argue that, prior to the introduction of data, naturalism trumps theism on the grounds of simplicity and that none of the data that we consider favours theism over naturalism. We conclude that, given the data considered, naturalism wins.” (Oppy, The Best Argument Against God, p18)

This is a logically valid argument. If it were the case that the data that we observe in the world didn’t favour theism over naturalism, then by Ockham’s Razor, the simpler view of naturalism should be preferred. However, while this is a logically valid argument, it is by no means a sound argument, because the premise that the data that we observe doesn’t at all favour theism, is contested by every single theist in the world.

Oppy therefore attempts to refute some of the common arguments put forward by theists, e.g. the cosmological argument, the argument from fine-tuning, the moral argument etc. However, Oppy’s counter-arguments rest on very contested premises, which is why theists don’t find them convincing, and why Oppy’s Best Argument Against God has largely gone ignored.

For example, on the cosmological argument (that the universe had an uncaused cause i.e. God), Oppy makes a false equivocation with an ill-defined term ‘causal stuff’ to argue that there is no difference between theistic views of the origin of the universe, and atheistic views of the origin of the universe. He writes:

“Given that Naturalist and Theist have exactly the same options when it comes to explaining why there is causal stuff rather than complete absence of causal stuff – each can hold that it is necessary that there is causal stuff, and each can hold that it is a brute fact that there is causal stuff – considerations about global causal structure do not count in favour of one view rather than the other.” (Oppy, The Best Argument Against God, p24)

In other words, Oppy believes that the view that there is a creator of the universe, and the view that there is no creator of the universe, have exactly the same options when it comes to explaining the creation of the universe. There is simply no theist in the world who would grant this. When it comes to weighing arguments for the origin of the universe, there is a significant difference between the view that there is a creator of the universe, and the view that there isn’t.

And yet, when Oppy comes to examining the cosmic fine-tuning, he makes exactly the same move. Oppy argues that the view that there is a designer, and the view that there is no designer, are somehow on equal footing when it comes to explaining the evidence for design. In Oppys words:

“Given that Theist and Naturalist have exactly the same options when it comes to explaining why the cosmic parameters that characterise our universe take the values that they do – each can hold that it is necessary that those cosmic parameters take the values that they do, and each can that it is brutely contingent that those cosmic parameters take the values that they do – it seems that we should conclude that considerations about the values of those parameters do not favour one of those views above the other.” (Oppy, The Best Argument Against God, p28-29).

The problem is that theists and naturalists don’t have the same options when it comes to explaining the cause of the universe, and the cosmic parameters that characterise our universe. Theists believe in a supernatural creator of the universe who designed the universe for life. Naturalists, by definition, don’t believe precisely that.

However, for all of the theistic arguments that Oppy engages with, he constantly skates over the relevant differences between theism and naturalism, in order to assert that any and every argument for theism is not actually an argument for theism at all. Even on the moral argument (that theism better explains moral truth), Oppy asserts that: “if there are explanations of moral truth, those explanations are unlikely to advantage either Theist or Naturalist.” (Oppy, The Best Argument Against God, p44).

The one difference that Oppy is willing to grant is simplicity. Naturalism posits one less entity than monotheism, and so for Oppy, naturalism therefore wins. If this was the only difference between theism and naturalism (as Oppy asserts), then Oppy would certainly have an argument. But it isn’t, and this is recognised by every theist in the world, and every naturalist except one.

This is the reason why Oppy’s Best Argument Against God is akin to coming across an elaborate sandcastle (above) and saying “This sandcastle came up by chance after millions of years of erosion.” It’s the simpler explanation, everything else is irrelevant (apparently), and so therefore it wins. However, for those who recognise the differences between theism and naturalism (other than simplicity), Oppy’s argument is reduced to precisely this: chance and erosion is a simpler explanation for the sandcastle, therefore chance and erosion wins.

Unfortunately (for Oppy’s argument), this is not how deductive reasoning works. When a doctor is diagnosing a patient, they don’t assert that positing a medical condition has exactly the same options to explain the symptoms as positing no underlying condition, and therefore the view that there is no underlying medical condition wins because it postulates fewer things.

When a detective is examining a crime scene, he doesn’t assert that the theory of a perpetrator has exactly the same options to explain the crime scene as the theory that there is no perpetrator, and therefore the theory that there is no perpetrator wins because it postulates fewer things.

And when a scientist is in the lab, they don’t assert that a hypothesis involving a cause has exactly the same options to explain an observation as the mere rejection of that hypothesis, and therefore the rejection of that hypothesis wins because it postulates fewer things.

But by Oppy’s logic, there’s no need of any explanations for anything. The one who posits a cause, or a designer, or an agent of any kind, has exactly the same explanatory options as the one who posits no cause, no designer, and no agent of any kind, and so we should all accept the view that there is no cause/designer/agent, simply because it posits one less entity.

This is why Oppy’s Best Argument Against God has largely gone ignored by theists. No one who understands it thinks that it’s a serious argument. And yet, atheists continue to point to Oppy’s work as one of the strongest cases against theism. While a number of atheists have pointed me to Oppy’s book, none of them have been able to articulate its argument. They’ve merely insisted that it’s a strong case, without being able to tell me what it is.

This is perhaps the most telling feature of Oppy’s Best Argument Against God. It’s so inaccessible that very few people understand it, and those who do understand it, recognise that it amounts to explaining something infinitely more complex than the most elaborate sandcastle, as something without a cause or a designer, simply because of a preference for simplistic explanations. This is, apparently, The Best Argument Against God.